1. Field of the Invention
The present invention relates generally to devices used to clear obstructions in body passage ways, and more particularly, relates to means and methods of treating such obstructions by the infusion of chemical thrombolytic agents.
2. Description of the Prior Art
The use of catheter systems to treat various medical conditions has been known for some time. In treating a particular area within a body passage way, it is often desirable to isolate the treatment area from the rest of the body through the use of one or more balloons which may be inflated proximal and/or distal to the treatment area. U.S. Pat. No. 2,936,760 issued to Gants, U.S. Pat. No. 4,022,216 issued to Stevens, and U.S. Pat. No. 4,705,502 issued to Patel describe catheters designed for use in the urinary tract.
Such catheter systems are also used in other applications. U.S. Pat. No. 4,696,668 issued to Wilcox, for example, describes a catheter system for treatment of nasobiliary occlusions. Similarly, U.S. Pat. No. 4,198,981 issued to Sinnreich is used in intrauterine applications. U.S. Pat. No. 4,453,545 issued to Inoue teaches an endotracheal tube.
One of the most common applications for catheter systems is the treatment of occlusions within the cardiovascular system. A catheter system for venous applications is seen in U.S. Pat. No. 4,795,427 issued to Helzel. U.S. Pat. No. 4,636,195 issued to Wollinsky, U.S. Pat. No. 4,705,507 issued to Boyles, and U.S. Pat. No. 4,573,966 issued to Welkl et al., all describe catheter systems designed to infuse a liquid for the treatment of an arterial occlusion. Each of these devices has one or more balloons to occlude the artery during the treatment process.
U.S. Pat. No. 4,655,746 issued to Daniels et al. proposes the use of two concentric catheters each having its own occlusion balloon to adjustably isolate a portion of the body passage way. The Daniels et al. design, however, requires the use of the interlumenal space as a fluid passageway, thereby complicating the construction and operation of the device. Use of the interlumenal space as a fluid passageway also may undesirably alter the handling characteristics depending upon the specific application and the degree to which the interlumenal space is pressurized.
A recognition of the need the improve to efficiency of the infused liquid is found in U.S. Pat. No. 4,423,725 issued to Baran et al. Unfortunately, the system of Baran et al. employs a middle balloon for forcing the liquid into the side walls of the artery. For arteries having insufficient resiliency, the high pressures in the isolated area tend to be equalized by expelling fluid and/or occluding material past the occluding balloons and out of the treatment area. In extreme cases, rupture of the arterial wall may be envisioned.